Safety Study of Hepatitis E Vaccine (HEV239)

Inclusion Criteria

• Subject must provide written informed consent.
• Subject must be able to comprehend and willing to comply with all study visits and procedures (up to 13 months from enrollment).
• Subject must be a man or a non-pregnant woman* aged 18-45 years (inclusive).

*Females of childbearing potential must have a negative serum human chorionic gonadotropin (beta-HCG) pregnancy test at screening and negative urine beta-HCG pregnancy test within 24 hours prior to (each) vaccination.

• Subject must be in good general health as determined by medical history, vital signs*, body mass index (BMI)**, physical examination, and clinical judgment of the investigator.

*Oral temp / = 18.5 and / = 1 year.

**Abstinence (defined as refraining from heterosexual intercourse), monogamous relationship with vasectomized partner, barrier methods such as male or female condoms with spermicide or diaphragms with spermicide, intrauterine devices, and licensed hormonal methods (such as birth control pills, skin patches, Implanon(R), Nexplanon(R), DepoProvera(R), or NuvaRing(R)).

• Male subjects must be surgically sterile via vasectomy OR must use an acceptable method of contraception* from prime vaccination until at least 3 months after the last boost vaccination.
• Abstinence (defined as refraining from heterosexual intercourse), or condoms with spermicide.
• Subjects must have consistent access to the internet to perform electronic data entry.

Exclusion Criteria

• Has a previous HEV infection or chronic liver disease.
• Has received any experimental agent* within 30 days prior to first vaccination, or the expected recipient of any experimental agent during this trial-reporting period.

*Including vaccines, drugs, biologics, devices, and/or blood products.

• Female subject is pregnant (or has a positive pregnancy test prior to vaccination) or breast feeding, or planning to become pregnant within 3 months after the last boost vaccination.
• Fever (> / = 38.0 Degrees Celsius / 100.4 Degrees Fahrenheit) or other acute illness within 3 days prior to first vaccination.
• Infection requiring systemic antibiotics or antiviral treatment within the 7 days prior to first vaccination.
• Has a positive urine drug screen for amphetamines*, cocaine, opiates, or phencyclidine.

*Prescription amphetamines are not exclusionary.

• Chronic, clinically significant medical or psychiatric conditions* that, in the opinion of the investigator, may pose additional risk to the subject if she/he participates in the study.

*Permissible conditions include but are not limited to mild, well-controlled asthma, well-controlled depression, well-controlled anxiety, seasonal allergies, and well-controlled hypertension.

• Receipt of immunosuppressive drugs*, **,*** or biologic agents within the 30 days prior to enrollment.

*This includes use of oral or parental prednisone. This also includes allergy desensitization injections from 14 days prior to each vaccination through 14 days after each vaccination. The use of topical steroids for mild uncomplicated dermatitis permissible after therapy is completed. Over-the-counter (OTC) corticosteroid nasal sprays for allergic rhinitis are permissible. The use of low or moderate dose inhaled steroids is permissible. Doses are defined as per age as using inhaled high-dose per reference chart in the National Heart, Lung and Blood Institute Guidelines for the Diagnosis and Management of Asthma (EPR-3) or other lists published in UPTODATE.

**Receipt of systemic, prescription medications for the treatment of chronic medical conditions or variations of normal physiologic functions may be permissible if, in the opinion of the investigator, they are used for conditions that are not clinically significant and would not impact the safety of the subject or the safety and immunogenicity outcomes of the protocol.

***Use of systemic, over-the-counter medications and PRN systemic, prescription medication may be allowed if, in